Is It Normal to Still Have Pain Three Months After a Knee Replacement?

Three months after a knee replacement, the leg should be fully recovered, so why does it still ache, and why is it sore on the stairs? This is the question that worries patients most after surgery, and it stems from a common misunderstanding, which is that a new joint should mean no pain straight away. In fact, pain after a knee replacement improves along a slope and not with the flick of a switch. Residual pain at three months or so mostly means that the recovery curve has not yet finished, and it rarely means the operation has failed.

A dull ache for several months after a knee replacement mostly does not mean the operation has failed. Research shows that about one in five people have residual pain at three months, and the proportion falls to about one in eight by one year, because the settling of swelling and healing of the soft tissues often takes a year to complete. However, redness, swelling and fever, pain that does not ease at rest, or pain that is becoming more obvious, calls for an immediate return visit to rule out infection or loosening of the prosthesis. For how long the swelling itself takes to settle and how to tell whether pain and numbness are normal, read the parent article on swelling and pain after a knee replacement first. This page concentrates on the time course and causes of residual pain that is still present after several months.

Still feeling pain several months after surgery mostly means recovery has not finished and is not the final result. An updated systematic review combined with Bayesian meta-analysis that followed knee replacement patients found that the proportion of patients with unsatisfactory pain falls over time and does not stay where it is (Cheng 2025). Calculated from higher-quality studies, the proportion of people who still have pain in the long term after knee replacement is about 20% (Beswick 2012). In other words, pain at this point is a stage on the way to recovery, and there is a good chance that it will keep improving.

How common residual pain after knee replacement is and how quickly it fades

Objective figures are the most reassuring. Calculated from higher-quality studies, the proportion with an unsatisfactory long-term pain outcome after knee replacement is about 20%. The original systematic review gave a range of 10% to 34% for the whole knee group, narrowing to about 20% in high-quality studies (Beswick 2012). The updated systematic review with Bayesian meta-analysis then looked at the time course in more detail and found that the proportion with unsatisfactory pain fell from 21.9% at three months to 14.1% at six months and 12.6% at twelve months (Cheng 2025). The proportion narrowing from about one in five to about one in eight shows that most residual pain does improve with time.

21.9%

Residual pain three months after surgery

The proportion whose pain improvement is not satisfactory, about one in five (Cheng 2025)

12.6%

Twelve months after surgery

The proportion falls to about one in eight (95% CrI 9.9 to 15.9%; Cheng 2025)

About 20%

Long-term reference proportion in high-quality studies

Full range 10% to 34% (Beswick 2012)

One further point should be added. A cross-sectional study at 3 to 4 years after surgery found that 44% of patients reported persistent pain after surgery of some degree, 15% reported it as severe to extreme, and only 6% of the patients had pain that was neuropathic in nature (Wylde 2011). In other words, some dull ache after surgery is quite common, but severe pain that is truly troublesome affects only a minority, and purely neuropathic pain is a minority within that minority. Most residual pain is a dull ache, tenderness or a feeling of weakness, which is just what is expected while the soft tissues have not fully settled.

Several causes of persistent pain after surgery

Persistent pain does not come from one single cause, and several possibilities are involved. An analysis of the causes of painful knees (122 painful knees) found that causes inside the joint accounted for 68% (loosening 48.2%, polyethylene wear 19.3%, instability 12% and others) and causes outside the joint for 32% (spinal nerve compression 25.6%, hip degeneration or avascular necrosis of the femoral head 15.4% and others). Even with a thorough work-up, 18.9% remained of unknown cause (Lim 2017). The main directions to watch for are as follows:

Soft tissue not yet settled (most common, most benign)The surgical incision, the joint capsule and the surrounding soft tissue need a year to heal completely. During this period a dull ache around the kneecap, tenderness on pressure and a feeling of weakness are very common (Wylde 2011). This kind of pain usually decreases slowly each month and is part of the normal recovery process.

Neuropathic pain / central sensitisationIn a minority of patients, residual pain has a burning or stabbing quality or the skin is oversensitive (in the Wylde 2011 study, only 6% had this kind of nerve pain). A systematic review shows that patients who already had symptoms of this nerve pain before surgery had a risk ratio of 2.75 of developing chronic pain after surgery (Gonzalez 2025). This kind of pain needs targeted pain management and cannot be left to fade with time alone.

Mechanical causes inside the joint (to be investigated)Loosening of the prosthesis, wear of the plastic insert and joint instability together account for nearly 80% of the causes of pain after knee replacement (Lim 2017). If, besides pain, the knee hurts sharply when starting to walk, feels as if it catches, or feels unsteady, this is not a simple soft tissue problem, and the patient must return to the doctor for an X-ray.

Causes outside the joint / referred painCompression of a lumbar nerve or degeneration of the hip can both refer pain to the knee (in the Lim 2017 study these made up most of the causes outside the knee joint). So when pain persists after knee replacement, the problem may not lie in the knee itself, and the physiotherapist will usually examine the lumbar spine and hip as well.

Telling improving recovery from recovery that has stalled

Among patients who all still have pain several months after surgery, the course afterwards can differ greatly. A longitudinal trajectory analysis identified two pain trajectories, "optimal improvement" and "sub-optimal improvement". Patients who improved more slowly in the first six months had more pain, worse function and lower satisfaction at 24 months (Yang 2019). This finding has a direct clinical message: the early recovery window affects the long-term outcome, and taking an active part in physiotherapy may turn a trajectory from "stuck" to "improving".

Improving trajectory

Pain falls month by month, with the proportion narrowing from about one in five at three months to about one in eight at one year (Cheng 2025)
Clear improvement in the first six months, with function and confidence recovering together (Yang 2019)
A dull ache that appears after activity and eases with rest, in keeping with the pace of soft tissue healing
Active work on knee flexion and quadriceps training, with steady gains from practice

Stuck trajectory

Slow improvement in the first six months, with more pain and worse function at 24 months (Yang 2019)
Training stopped because of the pain, which leaves the patient waiting passively
Neuropathic-like pain or central sensitisation before surgery that was not specifically addressed (Gonzalez 2025)
Pain with a burning or stabbing quality that does not ease even at rest, which suggests that more active pain management is needed

Who is more likely to have residual pain after surgery

Managing expectations has to be applied at the level of the individual. A systematic review with meta-analysis (32 studies, nearly 30,000 patients) found that catastrophising thoughts, mental health status, severity of knee pain before surgery and pain in other parts of the body were the strongest independent predictors of persistent pain after knee replacement (Lewis 2015). This means that the state before surgery gives some warning of the pain response afterwards. Having these factors does not mean the pain cannot improve. It indicates that these patients need active rehabilitation training with professional supervision more than most, and should not stop exercising because of ongoing pain.

Condition before surgery (Lewis 2015)

Catastrophising thoughts, meaning overly negative thoughts about pain
Poorer mental health, or emotional distress
Very severe knee pain before the operation
Pain in other parts of the body at the same time

Nerve-related factors (Gonzalez 2025)

Symptoms like nerve pain before surgery (PainDETECT ≥13)
The risk ratio of chronic pain after surgery is 2.75 (95% CI 1.78 to 4.26)
The central nervous system was already over-sensitive before surgery, and these patients are less likely to have a large improvement in pain after surgery
This is also linked to lower satisfaction after surgery

Warning signs that call for an immediate return visit

Most residual pain follows the normal recovery course, but the unusual features below should be treated as red flags and prompt a return visit as soon as possible. The key principle is that pain is the most common presentation of periprosthetic infection, so any persistent pain after knee replacement should be assessed first for the possibility of infection (Otto-Lambertz 2017). Chronic or delayed infection does not always show the typical redness, swelling and heat. Its main presentation is often persistent pain in the joint, sometimes with loosening of the prosthesis. A sinus tract at the wound confirms infection.

If any of the following occur, do not simply wait. Return to the doctor as soon as possible:

Pain that cannot be relieved at rest or when sleeping at night (normally a dull ache after activity improves with rest)
Pain that is not getting less and is getting worse (normally it should decrease slowly each month)
A red, swollen, warm joint, or even fever. Because bacterial infection most often presents as pain, this possibility must be ruled out first (Otto-Lambertz 2017)
Persistent wound discharge, or a sinus tract leading to deeper tissue (a sinus tract confirms infection)
Sharp pain when starting to walk, a feeling that the joint catches, or unsteadiness, which may mean the artificial joint has loosened (Lim 2017)
If any one of the above symptoms occurs, contact the surgeon at once for a detailed examination

Waiting times in Hong Kong public hospitals and linking up with physiotherapy after surgery

The knee replacement pathway in Hong Kong puts many patients in the group at higher risk of residual pain from the start. Waiting times for knee replacement in public hospitals are often counted in years, and many older adults have put up with pain for a long time before surgery, which leads to very severe knee pain before surgery. Severe knee pain before surgery is an independent predictor of persistent pain after surgery (Lewis 2015). Patients also usually go home about seven days after surgery, when the knee is still swollen and sore and climbing stairs is weak for the first few months, so it is all the more important to carry out rehabilitation training fully at home. The practical points locally are as follows:

Know the stages of rehabilitation in the public hospital—The Hospital Authority's total joint replacement centres cover 6 public hospitals with about 2,000 operations a year, and from 2020/21 have offered pre-operative non-surgical physiotherapy to patients on the waiting list (Hospital Authority website ha.org.hk, total joint replacement page). From the day of surgery until discharge, the hospital physiotherapists lead the patient through rehabilitation in stages. This includes ankle pump exercises and deep breathing in bed, practising walking beside the bed with a walking frame on the first day after surgery, and then reducing the support gradually to move on to walking independently.
Practise at home to suit the building—Many older adults in Hong Kong live in old tenement buildings or public housing without a lift, where stairs must be used to go in and out, and the toilet at home also needs to be changed from a squat toilet to a seat toilet. At home, the patient can do ankle bends and thigh-tightening exercises beside the bed to help bring down swelling, and practise standing up from the bed or a chair with a walking frame. Even if the home is cramped, the training can still be done, but a suitable spot should be arranged beforehand.
Do not stop practising while there is residual pain—The first six months are the key window for changing the trajectory (Yang 2019). Stopping because of ongoing pain makes it easy to fall into the sub-optimal trajectory. To restore the range of knee flexion and quadriceps strength, see the approach to regaining quadriceps strength after the swelling has settled in the same cluster of articles.

Clinically, when a home physiotherapist takes over an older adult with a knee replacement who has just been discharged, the family's first question is usually: "It is still swollen and painful at three months. Has something been damaged?" The therapist uses the objective figures on how residual pain falls over time (about one in five at three months, down to about one in eight at one year) to help the family manage expectations, and teaches them to tell apart a dull ache that decreases month by month from redness, swelling and fever, or pain that does not ease at rest. In the latter case the patient is referred for a return visit at once. This eases the anxiety of the patient and the family without missing serious problems such as infection or loosening. If the swelling itself is slow to settle, the patient can also check, with our article on how long knee swelling takes to subside, whether the situation is still within the normal range. As for the role of physiotherapy equipment (such as cold therapy machines and electrotherapy) during the residual pain period, expectations are often too high, and our article on myths about passive treatment devices explains this. Passive devices should never replace active training.

For high-risk patients who have put up with pain for a long time before surgery and have a low mood, the registered physiotherapists at Nova Health provide physiotherapy at home to help the patient regain knee flexion, quadriceps strength and walking confidence as early as possible, making good use of the first six months after surgery as the key window for changing the recovery trajectory. Research shows that passive waiting makes it easy for patients to fall into a sub-optimal recovery trajectory (Yang 2019), and that active, graded training is the practical way to move residual pain toward the improving curve.

Key points

Still feeling pain three months after a knee replacement mostly does not mean the operation has failed. Research shows that the proportion of patients with unsatisfactory pain falls from 21.9% at three months after surgery to 12.6% at twelve months (Cheng 2025), which is from about one in five to about one in eight.
Calculated from high-quality studies, the proportion with unsatisfactory long-term pain after knee replacement is about 20% (overall range of studies 10% to 34%, Beswick 2012). At 3 to 4 years after surgery, 44% of patients reported persistent pain of some degree, but only 6% of them had nerve pain (Wylde 2011).
The causes of persistent pain fall into those inside the joint (such as component loosening, wear and instability, about 68%) and those outside the joint (such as pain referred from the lumbar spine or hip, about 32%), and 18.9% have no specific cause found (Lim 2017). Most residual pain simply means that the soft tissues have not yet fully recovered and is benign.
People more likely to have residual pain include those with very severe knee pain before surgery, pain in several parts of the body, catastrophising thoughts about pain and emotional distress (Lewis 2015), and those who already had symptoms like nerve pain before surgery (risk ratio 2.75, Gonzalez 2025). These patients need active rehabilitation training more than most, and the first six months after surgery are the key period for improving recovery (Yang 2019).
Warning signs call for an immediate return visit. They include pain that is not eased at rest or at night, pain that is getting worse, redness, swelling and fever, wound discharge or a sinus tract, and sharp pain or catching when starting to walk. Because bacterial infection most often presents as pain, it must be checked for first (Otto-Lambertz 2017; Lim 2017).

Frequently asked questions

I still have swelling and a dull ache three months after my knee replacement. Has the operation failed?

In most cases, no. A systematic review shows that about 21.9% of patients still have unsatisfactory pain at three months, falling to about 12.6% at one year (Cheng 2025). This indicates that most residual pain improves as swelling settles and the soft tissues heal. What really calls for alertness is pain that is not relieved even at rest, pain that is becoming more obvious, or pain with redness, swelling or fever. In those situations the patient should seek medical help at once for investigation.

How long until a knee replacement is completely pain-free?

The clinical consensus is that improvement is fastest in the first 6 to 12 months, but the soft tissues take a year, or even a year and a half, to settle completely. An occasional ache, or pain when the weather changes, is normal during this period. If obvious pain that affects daily life is still present after a year, a return visit for further assessment is worthwhile. (This time frame is mostly clinical consensus and extrapolation from patient guidance, and is not a figure from a single RCT.)

How can normal recovery pain be told apart from pain that needs medical attention?

Normal recovery pain usually fades month by month. It tends to appear as a dull ache after activity that eases with rest. Symptoms that call for alertness include pain that is not relieved at rest or at night, a red, swollen or warm joint, fever, wound discharge, or sharp pain when starting to walk. Because pain is the most common presentation of periprosthetic infection, infection must be ruled out first when any of these appear (Otto-Lambertz 2017; Lim 2017).

Why are patients who were in a lot of pain before surgery especially prone to residual pain afterwards?

Research consistently shows that the risk of persistent pain after surgery is higher if the patient had severe knee pain before surgery, pain in other parts of the body, catastrophising thoughts or emotional distress, or already had neuropathic-like pain or central sensitisation before surgery (the risk ratio for neuropathic-like pain reached 2.75; Gonzalez 2025). Having these factors does not mean the pain cannot improve. It indicates that the patient needs to take a more active part in pain management and rehabilitation training.

Is It Normal to Still Have Pain Three Months After a Knee Replacement? How Residual Pain Improves Over Time